btrfs: fiemap: preallocate ulists for btrfs_check_shared

btrfs_check_shared looks up parents of a given extent and uses ulists
for that. These are allocated and freed repeatedly. Preallocation in the
caller will avoid the overhead and also allow us to use the GFP_KERNEL
as it is happens before the extent locks are taken.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 982152d..89116af 100644 (file)
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -1465,12 +1465,11 @@ int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
  *
  * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
  */
-int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
+int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr,
+               struct ulist *roots, struct ulist *tmp)
 {
        struct btrfs_fs_info *fs_info = root->fs_info;
        struct btrfs_trans_handle *trans;
-       struct ulist *tmp = NULL;
-       struct ulist *roots = NULL;
        struct ulist_iterator uiter;
        struct ulist_node *node;
        struct seq_list elem = SEQ_LIST_INIT(elem);
@@ -1481,12 +1480,8 @@ int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
                .share_count = 0,
        };
 
-       tmp = ulist_alloc(GFP_NOFS);
-       roots = ulist_alloc(GFP_NOFS);
-       if (!tmp || !roots) {
-               ret = -ENOMEM;
-               goto out;
-       }
+       ulist_init(roots);
+       ulist_init(tmp);
 
        trans = btrfs_attach_transaction(root);
        if (IS_ERR(trans)) {
@@ -1527,8 +1522,8 @@ int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
                up_read(&fs_info->commit_root_sem);
        }
 out:
-       ulist_free(tmp);
-       ulist_free(roots);
+       ulist_release(roots);
+       ulist_release(tmp);
        return ret;
 }
 

diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
index 54d5898..777f61d 100644 (file)
--- a/fs/btrfs/backref.h
+++ b/fs/btrfs/backref.h
@@ -57,7 +57,8 @@ int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
                          u64 start_off, struct btrfs_path *path,
                          struct btrfs_inode_extref **ret_extref,
                          u64 *found_off);
-int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr);
+int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr,
+               struct ulist *roots, struct ulist *tmp_ulist);
 
 int __init btrfs_prelim_ref_init(void);
 void __cold btrfs_prelim_ref_exit(void);

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index db337e5..441f6c4 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4542,6 +4542,8 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
        struct btrfs_path *path;
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct fiemap_cache cache = { 0 };
+       struct ulist *roots;
+       struct ulist *tmp_ulist;
        int end = 0;
        u64 em_start = 0;
        u64 em_len = 0;
@@ -4555,6 +4557,13 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                return -ENOMEM;
        path->leave_spinning = 1;
 
+       roots = ulist_alloc(GFP_KERNEL);
+       tmp_ulist = ulist_alloc(GFP_KERNEL);
+       if (!roots || !tmp_ulist) {
+               ret = -ENOMEM;
+               goto out_free_ulist;
+       }
+
        start = round_down(start, btrfs_inode_sectorsize(inode));
        len = round_up(max, btrfs_inode_sectorsize(inode)) - start;
 
@@ -4566,7 +4575,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                        btrfs_ino(BTRFS_I(inode)), -1, 0);
        if (ret < 0) {
                btrfs_free_path(path);
-               return ret;
+               goto out_free_ulist;
        } else {
                WARN_ON(!ret);
                if (ret == 1)
@@ -4675,7 +4684,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                         */
                        ret = btrfs_check_shared(root,
                                                 btrfs_ino(BTRFS_I(inode)),
-                                                bytenr);
+                                                bytenr, roots, tmp_ulist);
                        if (ret < 0)
                                goto out_free;
                        if (ret)
@@ -4721,6 +4730,10 @@ out:
        btrfs_free_path(path);
        unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1,
                             &cached_state);
+
+out_free_ulist:
+       ulist_free(roots);
+       ulist_free(tmp_ulist);
        return ret;
 }